— I beg your pardon,but I didn’t quite catch you.— Oh,I ____

个人觉得这句话问的本身有点语病.语感完全不通顺.
I beg your pardon, but I didnt quite catch you.
请你重复一下, 但是我没有听到.
我觉得改一下好一点
I beg your pardon. In fact, I didnt catch you properly.
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回归到问题：
Oh,I am/was talking to myself. 感觉都可以,看语境.

你好
oh I was talking to myself.
希望能够一定程度上帮你解答你的疑惑,望采纳.有什么问题的话我们可以继续探讨的哈!

was talking to oneself，自言自语
A:你能重复一遍吗？我没有跟上你说的话 B:：哦，刚才我在自言自语呢回复
注意是刚才